Close any open overlays when leaving the change page

The change page is only recreated when the change number changes. This
means any open overlays are not closed hence close them explicitly
when the view changes.

Google-bug-id: b/190376531
Change-Id: I892c6321cbad0ec7914f05d03551d0977b131da1
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
index ced66a9..e278e03 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
@@ -52,7 +52,7 @@
 } from '../../../mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin';
 import {GrEditConstants} from '../../edit/gr-edit-constants';
 import {pluralize} from '../../../utils/string-util';
-import {windowLocationReload} from '../../../utils/dom-util';
+import {windowLocationReload, querySelectorAll} from '../../../utils/dom-util';
 import {
   GeneratedWebLink,
   GerritNav,
@@ -1173,6 +1173,9 @@
   _paramsChanged(value: AppElementChangeViewParams) {
     if (value.view !== GerritView.CHANGE) {
       this._initialLoadComplete = false;
+      querySelectorAll(this, 'gr-overlay').forEach(overlay =>
+        (overlay as GrOverlay).close()
+      );
       return;
     }